Imide-Terminated Prepolymer, Preparation Method Therefor, Curable Resin Composition, Use Thereof and Dual Curing Method

ABSTRACT

Provided are an imide-terminated prepolymer, a preparation method therefor, a curable resin composition, use thereof and a dual curing method. An end capped, imide-terminated prepolymer is mixed with at least one photopolymerizable ethylenic monomer, at least one photoinitiator and diamine, and optionally a pigment to form a curable resin composition, which, in a first step, is irradiated under conditions effective to polymerize the at least one ethylenic monomer. The irradiated composition is then heat-treated under conditions effective to cause a transimidation reaction between the prepolymer and the diamine to provide a solid polymer.

TECHNICAL FIELD

The disclosure relates generally to the fabrication of three-dimensional objects, and more particularly relates to a technique for obtaining a 3D article by means of “dual curing” by using an imide-terminated prepolymer.

BACKGROUND

Three-dimensional (3D) printing typically involves the production of 3D objects via an additive manufacturing (AM) process. Additive manufacturing was originally developed in the early 1980s, and made use of UV-curable liquid resins to form thermoset polymers. A solid structure was built up in layers, with each layer corresponding to a crosssectional slice of the structure and formed by deposition and photocure of the liquid resin. A stereolithographic additive (SLA) manufacturing process was developed several years later, in which a cross-sectional pattern of the object to be formed was created as digital data, and the object then formed according to the pattern. There have been many developments in the field of 3D printing since then, and many improvements and refinements have been made to the basic additive manufacturing process. For example, speed and accuracy have drastically improved, thus enabling the manufacture of extremely small or complex structures with extraordinary precision.

AM is currently implemented on a large-scale commercial level in many fields of use, from the “bioprinting” of blood vessels and organs to integrated circuit manufacture; Fabrication of prototypes can be carried out quickly and inexpensively via SLA “rapid prototyping” a time- and cost-saving commercial advantage; and the cost of 3D printing materials and equipment has dropped to the point where the technology is accessible to individuals and small businesses as well as large organizations.

However, not only rapid prototyping needs to be achieved, but also mechanical performance requirements of end articles need to be satisfied, there remains a need for improvement.

In addition, materials are the key to 3D printing technology to create a new terminal manufacturing market.

SUMMARY OF THE DISCLOSURE

Therefore, the present disclosure relates to a polymer, a composition containing the polymer, and a three-dimensional object that solve the aforementioned needs in the field.

In one embodiment, the present disclosure provides an end-capped, imide-terminated prepolymer, the prepolymer has the structure of formula (I):

wherein:

L comprises an oligomeric hydrocarbylene moiety that is unsubstituted, substituted, heteroatom-containing, or substituted and heteroatom-containing;

Ar is aryl;

R¹ and R³ may be the same or different and are divalent linking group;

q and r are both 1; and

R² and R⁴ are imide end-capping groups that can be removed in transimidization reaction.

According to a preferred embodiment, in formula (I), Ar is a monocyclic aryl group; and more preferably, Ar does not contain a heteroatom. Preferably, Ar benzene, such that the prepolymer has the structure of formula (II),

In another related aspect, the prepolymer has a weight average molecular weight in the range of about 500 to about 5000.

In another embodiment, the present disclosure provides a method for synthesizing an end capped, imide-terminated prepolymer, the method comprises:

(a) contacting at least one o-aryl dicarboxylic anhydride having a structure of formula (A1) and at least one amine-terminated oligomer having a structure of formula (XVI) at a molar ratio of at least 2:1 under conditions effective to produce an o-aryl dicarboxylic anhydride-terminated oligomer as a reaction article to obtain an o-aryl dicarboxylic anhydride-terminated oligomer; and

(b) mixing and reacting at least one amine-substituted reactant having a structure of formula (A2) with the o-aryl dicarboxylic anhydride-terminated oligomer at a molar ratio of at least 2:1 to obtain an end-capped, imide-terminated prepolymer;

NH₂—R⁴¹,   formula (A2)

in formula (A1), Ar is aryl group; R³¹ is selected from nonovalent linking groups containing an acid anhydride structure;

in formula (A2), R⁴¹ is selected from imide end-capping groups that can be removed in the transimidization reaction;

in formula (XVI), L contains unsubstituted, substituted, heteroatom-containing, or substituted and heteroatom-containing oligoalkylene moieties.

In a further embodiment, the disclosure provides a method for synthesizing the end-capped imide-terminated prepolymer wherein the synthetic method comprises:

(a) combining a diphthalic anhydride with an amine-terminated oligomer at a molar ratio of at least about 2:1 under conditions effective to give a phthalimide-terminated oligomer as a reaction product; and

(b) end-capping the phthalimide-terminated oligomer by admixing an aminosubstituted cyclic reactant with the phthalimide-terminated oligomer at a molar ratio of at least about 2:1 at an elevated temperature for a reaction time of at least about 12 hours.

In another embodiment, the present disclosure provides a novel curable resin composition comprising the capped and imide-terminated prepolymer, at least one photopolymerizable ethylenic monomer, at least one photoinitiator, and a diamine, and optionally a pigment.

Preferably, the prepolymer in the novel curable resin composition is the aforementioned prepolymer.

In another aspect of any of the above-delineated embodiments, the photopolymerizable olefinic monomer serves as a reactive diluent.

In a related aspect, the photopolymerizable olefinic monomer is an acrylate or methacrylate monomer.

In another related aspect, the photopolymerizable olefinic monomer has the structure of formula (XIV),

wherein:

R⁵ is H or CH₃, and R⁶ is C₁ to C₁₆ hydrocarbyl, substituted C₁ to C₃₆ hydrocarbyl, heteroatom-containing C₁ to C₃₆ hydrocarbyl, or substituted and heteroatom-containing C₁ to C₃₆ hydrocarbyl.

In an additional aspect of any of the above-delineated embodiments, the diamine serves as a chain extender and has the structure of formula (XV),

H₂N—L¹—NH₂   formula (XV)

wherein L¹ is C₂ to C₁₄ hydrocarbylene, substituted C₂ to C₁₄ hydrocarbylene, heteroatom-containing C₂ to C₁₄ hydrocarbylene, or substituted and heteroatom-containing C₂ to C₁₄ hydrocarbylene.

In one embodiment, the present disclosure provides a dual curing method for forming a solid polymer, the method comprises:

(a) mixing the capped and imide-terminated prepolymer with at least one photopolymerizable ethylenic monomer, at least one photoinitiator, and a diamine, or optionally a pigment to form a curable resin composition;

(b) irradiating, the resin composition under conditions that effectively polymerize the at least one photopolymerizable ethylenic monomer; and

(c) subjecting the irradiated resin composition to heat treatment at temperatures of an imidization reaction between the prepolymer and the diamine to provide the solid polymer.

In the foregoing embodiment, in the step (a), “mixing the capped and imide-terminated prepolymer with at least one photopolymerizable ethylenic monomer, at least one photoinitiator, and a diamine, or optionally a pigment to form a curable resin composition” can be understood as mixing the capped and imide-terminated prepolymer with at least one photopolymerizable ethylenic monomer, at least one photoinitiator, and a diamine to form a curable resin composition; or mixing the capped and imide-terminated prepolymer with at least one photopolymerizable ethylenic monomer, at least one photoinitiator, a diamine, and a pigment to form a curable resin composition.

In the foregoing embodiment, in the step (b), after the irradiation, a scaffold formed from the resin composition contains the prepolymer and the polyolefin, and has the diamine physically trapped in the scaffold.

In the foregoing embodiment, in the step (c), after the heat treatment, the capping agent of the prepolymer can be released at the same time.

In a preferred aspect of the foregoing embodiment, the solid polymer corresponds to a three-dimensional object of a predetermined shape and size.

In a preferred aspect of the foregoing embodiment, between the step (a) and (b), the curable resin composition is added to a configuration area of which the shape and size respectively correspond to the predetermined shape and size of the three-dimensional object.

In another embodiment, the present disclosure provides a photocurable composition prepared by irradiating a curable resin composition with actinic radiation of a wavelength effective to cure a photopolymerizable ethylenic monomer, the curable resin composition comprises a capped and imide-terminated prepolymer, at least one photopolymerizable ethylenic monomer, at least one photoinitiator, and a diamine, and optionally a pigment.

In yet another embodiment, the present disclosure provides a solid composition prepared by a method comprising the following steps: (a) irradiating a curable resin composition comprising a capped and imide-terminated prepolymer, at least one photopolymerizable ethylenic monomer, at least one photoinitiator, and a diamine, and optionally a pigment, wherein the actinic radiation wavelength effectively cures the photopolymerizable ethylenic monomer, thereby providing a photocurable composition; and heating the photocurable composition provided in (a) under conditions that promote the transimidation reaction between the capped and imide-terminated prepolymer and the diamine.

It should be understood that in the implementation of the method above in the field of 3D printing, the solid polymer corresponds to a 3D object of a predetermined shape and size, as embodied in a 3D printable model, for example, computer-aided design (CAD) software package, 3D scanner or photogrammetry software which can work from two-dimensional digital images.

In an aspect of the foregoing embodiment, before the resin composition is irradiated in the step (b), the curable resin composition produced in the step (a) is added to the configuration area corresponding to the predetermined shape and size of the object.

In another embodiment, provided is a method for forming a layer of a 3D object, for example, a method that can be done in the context of an additive manufacturing process. The method comprises:

(a) mixing the capped and imide-terminated prepolymer with at least one photopolymerizable ethylenic monomer, at least one photoinitiator, and a diamine, or a pigment to form a curable resin combination;

(b) providing the curable resin composition as a layer on a substrate by coating, deposition or other means; and

(c) irradiating the layer under conditions that of polymerize the ethylenic monomer and provide a polyolefin in the layer to form a scaffold layer.

In a preferred aspect of the foregoing embodiment, provided is a method for forming a three-dimensional object layer in an additive manufacturing process, the method comprises:

(a) mixing (i) the capped and imide-terminated prepolymer with (ii) a photopolymerizable ethylenic monomer, (iii) at least one photoinitiator and (iv) a diamine, and optionally (v) a pigment to form a curable resin composition;

(b) providing the curable resin composition on a substrate to form a layer; and

(c) irradiating the layer under conditions of polymerizing the photopolymerizable ethylenic monomer.

Likewise, in the method for forming a layer of a 3D object, in the step (c), the scaffold layer comprises a prepolymer and a polyolefin, and has a diamine physically trapped therein.

In another embodiment, the present disclosure provides an improved method for forming a 3D object using an additive manufacturing method, the method comprises continuously forming a layer with a size corresponding to a 3D digital image in a computer-controlled manner on a substrate, the improved method comprises forming the layer by a method comprising the following steps:

(a) providing an initial curable layer on a substrate, wherein the layer comprises a curable resin composition prepared by mixing a capped and imide-terminated prepolymer, a photopolymerizable ethylenic monomer, at least one photoinitiator, and as diamine, and optionally a pigment;

(b) irradiating the initial curable layer under conditions that effectively polymerize the photopolymerizable ethylenic monomer to form a first scaffold layer;

(c) repeating the step (a) to provide an additional layer on the first scaffold layer;

(d) irradiating the additional layer under conditions that effectively polymerize the photopolymerizable ethylenic monomer and provide an additional scaffold layer;

(e) repeating steps (c) and (d) until the formation of the 3D object is completed; and

(f) subjecting the 3D object to heat treatment at a temperature effective to cause a transimidization reaction between the prepolymer and the diamine.

In the aforementioned improved method for forming a 3D object by using an additive manufacturing method, in the step (b), the first scaffold layer comprises a prepolymer and a polyolefin formed by effectively polymerizing the photopolymerizable ethylenic monomer, and the first scaffold layer comprises a diamine physically trapped therein.

In a preferred aspect of the foregoing embodiment, provided is a method for forming a three-dimensional object by using an additive manufacturing process, the method comprises continuously forming a layer having a size corresponding to a three-dimensional digital image on a substrate through computer control, and the improvement lies in that the method comprises forming the layer by the following steps:

(a) providing an initial curable layer on a substrate, wherein the initial curable layer contains a curable resin composition prepared by mixing a capped and imide-terminated prepolymer, a photopolymerizable ethylenic monomer, at least one photoinitiator, and a diamine, and optionally a pigment;

(b) irradiating the initial curable layer under conditions that polymerize the photopolymerizable ethylenic monomer to form a first scaffold layer;

(e) repeating the step (a) to provide an additional layer on the first scaffold layer;

(d) irradiating the additional layer under conditions that of polymerize the photopolymerizable ethylenic monomer;

(e) repeating steps (c) and (d) until the formation of the three-dimensional object is completed; and

(f) subjecting the three-dimensional object to heat treatment at a temperature effective to cause a transimidization reaction between the prepolymer and the diamine.

In another embodiment, the present disclosure provides a dual curing method for forming a solid polymer, the method comprising:

(a) (i) mixing bisphthalic anhydride and an amine-terminated oligomer at a molar ratio of at least about 2:1 under conditions effective to produce a bisphthalic anhydride-terminated oligomer as a reaction product to obtain a bisphthalic anhydride-terminated oligomer, and (ii) mixing the cyclic reactant substituted by the amino group with the bisphthalic anhydride-terminated oligomer at an elevated temperature at a molar ratio of at least about 2:1 for a reaction time of at least about 12 hours to obtain a capped and bisphthalimide-terminated oligomer;

(b) mixing the prepolymer with at least one photopolymerizable ethylenic monomer, at least one photoinitiator, and a diamine, and optionally a pigment, to form a curable resin composition;

(c) irradiating the resin composition under conditions of effectively polymerizing the at least one photopolymerizable ethylenic monomer, and forming a scaffold by the irradiation, wherein the scaffold comprises the prepolymer and a polyolefin formed by effectively polymerizing the at least one photopolymerizable ethylenic monomer, and has the diamine physically trapped therein; and

(d) subjecting the irradiated composition at a temperature that effectively causes as transimidization reaction between the prepolymer and the diamine, wherein the heat treatment can simultaneously release the end-capping agent in the prepolymer and provide a solid polymer.

According to another specific embodiment, the present disclosure provides a dual curing method for forming a solid polymer, the method comprising:

(a) synthesizing a capped and imide-terminated prepolymer according to the method described above;

(b) mixing the prepolymer with at least one photopolymerizable ethylenic monomer, at least one photoinitiator, and a diamine, and optionally a pigment, to form a curable resin composition;

(c) irradiating the resin composition under conditions that effectively polymerize the at least one photopolymerizable ethylenic monomer; and

(d) subjecting the irradiated composition at a temperature effective to cause a transimidation reaction between the prepolymer and the diamine.

In one embodiment, the present disclosure provides a method for forming a three-dimensional object layer in an additive manufacturing process, the method comprising:

(a) synthesizing a capped and imide-terminated prepolymer according to the method described above;

(b) mixing the prepolymer with at least one photopolymerizable ethylenic monomer, at least one photoinitiator, and a diamine, and optionally a pigment, to form a curable resin composition;

(c) providing the curable resin composition on a substrate to form a layer; and

(d) irradiating the layer under conditions that effectively polymerize the photopolymerizable ethylenic monomer.

In yet another embodiment, the present disclosure provides a method for forming a three-dimensional object layer in an additive manufacturing process, the method comprising:

(a) (i) mixing bisphthalic anhydride and an amine-terminated oligomer at a molar ratio of at least about 2:1 under conditions effective to produce a bisphthalic anhydride-terminated oligomer as a reaction product to obtain a bisphthalic anhydride-terminated oligomer, and (ii) mixing the cyclic reactant substituted by the amino group with the bisphthalic anhydride-terminated oligomer at an elevated temperature at a molar ratio of at least about 2:1 for a reaction time of at least about 12 hours to obtain a capped and bisphthalimide-terminated oligomer;

(b) mixing the prepolymer with at least one photopolymerizable ethylenic monomer, at least one photoinitiator, and a diamine, and optionally a pigment, to form a curable resin composition;

(c) providing the curable resin composition as a layer of a substrate; and

(d) irradiating the layer under conditions of effectively polymerizing the polymerizable ethylenic monomer to form a scaffold layer, wherein the scaffold layer comprises a prepolymer and a polyolefin formed by effectively polymerizing the polymerizable ethylenic monomer, and has the diamine physically trapped therein.

According to an embodiment, the present disclosure provides a dual curing method for forming a solid polymer, the method comprising:

(a) mixing (i) as prepolymer with end groups that covalently react with amines when heated, (ii) at least one photopolymerizable ethylenic monomer, (iii) at least one photoinitiator, and (iv) a diamine, and optionally a pigment, to form a curable resin composition;

(b) irradiating the resin composition under conditions that effectively polymerize the at least one of the photopolymerizable ethylenic monomers; and

(c) subjecting the irradiated composition at a temperature effective to cause a reaction between the end groups of the prepolymer and the diamine.

It should be noted that, in the present disclosure, during irradiation, the diamine in the curable resin composition does not undergo a reaction, and is only physically present therein.

In yet another embodiment, the present disclosure provides an article prepared by the method of any of the foregoing embodiments of the present disclosure; preferably, the article is a three-dimensional article.

In yet another embodiment, the present disclosure provides use of the prepolymer of any of the foregoing embodiments and the curable resin composition of any of the foregoing embodiments in forming an article preferably, the prepolymer and the curable resin composition are additively manufactured to form the article; and it is particularly preferred that the article is a three-dimensional article.

DETAILED DESCRIPTION OF THE DISCLOSURE

I. Nomenclature and Overview

Unless defined otherwise, all technical and scientific terms used herein have the meaning commonly understood by one of ordinary skill in the art to which the disclosure pertains. Specific terminology of particular importance to the description of the present disclosure is defined below.

In this specification and the appended claims, the singular forms “a”, “an” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, “a prepolymer” refers not only to a single prepolymer but also to a combination of two or more different prepolymers, “a diamine” refers to a single diamine or to a combination of diamines, and the like.

As used herein, the phrase “having the formula” or “having the structure” is not intended to be limiting and is used in the same way that the term “comprising” is commonly used.

The term “alkyl” as used herein refers to a branched or unbranched saturated hydrocarbon group containing 1 to about 24 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, octyl, decyl, and the like, as well as cycloalkyl groups such as cyclopentyl, cyclohexyl, and the like. Generally, although again not necessarily, alkyl groups herein contain 1 to about 18 carbon atoms, preferably 1 to about 12 carbon atoms.

The term “alkylene” as used herein refers to a difunctional linear, branched, or cyclic saturated hydrocarbon linkage containing 1 to about 24 carbon atoms, such as methylene, ethylene, n-propylene, n-butylene, n-hexylene, decylene, tetradecylene, hexadecylene, and the like. Preferred alkylene linkages contain 1 to about 12 carbon atoms, and the term “lower alkylene” refers to an alkylene linkage of 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms. The term “substituted alkylene” refers to an alkylene linkage substituted with one or more substituent groups, i.e., wherein a hydrogen atom is replaced with a non hydrogen substituent group, and the terms “heteroatom-containing alkylene” and “heteroalkylene” refer to alkylene linkages in which at least one carbon atom is replaced with a heteroatom. If not otherwise indicated, the terms “alkylene” and “lower alkylene” include linear, branched, cyclic, unsubstituted, substituted, and/or heteroatom containing alkylene and lower alkylene, respectively. Oligomeric and polymeric “alkylenes” are also envisioned herein, for example, a substituted or unsubstituted, optionally heteroatom-containing poly (ethylene).

The term “alkenyl” as used herein refers to a linear, branched or cyclic hydrocarbon group of 2 to about 24 carbon atoms containing at least one double bond, such as ethenyl, n-propenyl, isopropenyl, n-butenyl, isobutenyl, octenyl, decenyl, tetradecenyl, hexadecenyl, eicosenyl, tetracosenyl, and the like. Generally, although again not necessarily, alkenyl groups herein contain 2 to about 18 carbon atoms, preferably 2 to 12 carbon atoms. The term “lower alkenyl” intends an alkenyl group of 2 to 6 carbon atoms, and the specific term “cycloalkenyl” intends a cyclic alkenyl group, preferably having 5 to 8 carbon atoms. The term “substituted alkenyl” refers to alkenyl substituted with one or more substituent groups, and the terms “heteroatom-containing alkenyl” and “heteroalkenyl” refer to alkenyl in which at least one carbon atom is replaced with a heteroatom. If not otherwise indicated, the terms “alkenyl” and “lower alkenyl” include linear, branched, cyclic, unsubstituted, substituted, and/or heteroatom-containing alkenyl and lower alkenyl, respectively.

The term “alkenylene” as used herein refers to a difunctional linear, branched, or cyclic hydrocarbon linkage containing 7 to about 24 carbon atoms, such as ethenylene npropenylene, isopropenylene, n-butenylene, isobutenylene, octenylene, decenylene, tetradecenylene, hexadecenylene, eicosenylene, tetracosenylene, etc. Preferred alkenylene linkages contain 2 to about 12 carbon atoms, and the term “lower alkylene” refers to an alkylene linkage of 2 to 6 carbon atoms, preferably 2 to 4 carbon atoms. The term “substituted alkenylene” refers to an alkenylene linkage substituted with one or more substituent groups, wherein a hydrogen atom is replaced with a non-hydrogen substituent group, and the terms “heteroatom-containing alkenylene” and “heteroalkenylene” refer to alkenylene linkages in which at least one carbon atom is replaced with a heteroatom. If not otherwise indicated, the terms “alkylene” and “lower alkenylene” include linear, branched, cyclic, unsubstituted, substituted, and/or heteroatom-containing alkenylene and lower alkenylene, respectively. Oligomeric and polymeric “alkenylene linkages” are also envisioned herein, such as, a substituted or unsubstituted, optionally heteroatom-containing poly(ethylene) linker, which may form the body of an oligomer or polymer that bridges two end groups.

The term “aryl” as used herein, and unless otherwise specified, refers to an aromatic substituent containing a single aromatic ring or multiple aromatic rings that are fused together, directly linked, or indirectly linked (such that the different aromatic rings are bound to a common group such as a methylene or ethylene moiety). Preferred aryl groups contain 5 to 24 carbon atoms, and particularly preferred aryl groups contain 5 to 14 carbon atoms. Exemplary aryl groups contain one aromatic ring or two fused or linked aromatic rings, e.g., phenyl, naphthyl, biphenyl, diphenylether, diphenylamine, benzophenone, and the like. “Substituted aryl” refers to an aryl moiety substituted with one or more substituent groups, and the terms “heteroatom-containing aryl” and “heteroaryl” refer to aryl substituent, in which at least one carbon atom is replaced with a heteroatom, as will be described in further detail infra. If not otherwise indicated, the term “aryl” includes unsubstituted, substituted, and/or heteroatom-containing aromatic substituents.

The term “arylene” refers to a bivalent aromatic group, containing one to three aromatic rings, either fused or linked, and either unsubstituted or substituted with one or more substituents. Unless otherwise indicated, the term “arylene” includes substituted arylene and/or heteroatom-containing arylene.

The term “alkaryl” refers to an aryl group with an alkyl substituent, and the term “aralkyl” refers to an alkyl group with an aryl substituent, wherein “aryl” and “alkyl” are as defined above. Preferred aralkyl groups contain 6 to 24 carbon atoms, and particularly preferred aralkyl groups contain 6 to 16 carbon atoms. Examples of aralkyl groups include, without limitation, benzyl, 2-phenyl-ethyl, 3-phenyl-propyl, 4-phenyl-butyl, 5-phenyl-pentyl, 4-phenylcyclohexyl, 4-benzylcyclohexyl, 4-phenylcyclohexylmethyl, 4-benzylcyclohexylmethyl, and the like. Alkaryl groups include, for example, p-methylphenyl, 2,4-dimethylphenyl, p-cyclohexylphenyl, 2,7-dimethylnaphthyl, 7-cyclooctyinaphthyl, 3-ethyl-cyclopenta-1,4-diene, and the like. The terms “alkaryloxy” and “aralkyloxy” refer to substituents of the formula —OR wherein R is alkaryl or aralkyl, respectively, as just defined.

The term “acyl” refers to substituents having the formula —(CO)-alkyl, —(CO)-aryl, or —(CO)-aralkyl, and the term “acyloxy” refers to substituents having the formula —O(CO)-alkyl, —O(CO)-aryl, or —O(CO)-aralkyl, wherein “alkyl”, “aryl”, and “aralkyl” are as defined above.

The term “cyclic” refers to alicyclic or aromatic substituents that may or may not be substituted and/or heteroatom containing, and that may be monocyclic, bicyclic, or polycyclic.

The term “alicyclic” is used in the conventional sense to refer to an aliphatic cyclic moiety, as opposed to an aromatic cyclic moiety, and may be monocyclic, bicyclic, or polycyclic. Alicyclic compounds substituents may be heteroatom-containing and/or substituted, but are normally unsubstituted and do not contain heteroatoms, i.e., are carbocyclic.

The term “heteroatom-containing” as in a “heteroatom-containing alkyl group” (also termed a “heteroalkyl” group) or a “heteroatom-containing aryl group” (also termed a “heteroaryl” group) refers to a molecule, linkage or substituent in which one or more carbon atoms are replaced with an atom other than carbon, e.g., nitrogen, oxygen, sulfur, phosphorus or silicon, typically nitrogen, oxygen or sulfur, preferably nitrogen or oxygen. Similarly, the term “heteroalkyl” refers to an alkyl substituent that is heteroatom-containing, the term “heterocyclic” refers to a cyclic substituent that is heteroatom-containing, the terms “heteroaryl” and “heteroaromatic” respectively refer to “aryl” and “aromatic” substituents that are heteroatom-containing, and the like. Examples of heteroalkyl groups include alkoxyaryl, alkylsulfanyl-substituted alkyl, N-alkylated amino alkyl, and the like. Examples of heteroaryl substituents include pyrrolyl, pyrrolidinyl, pyridinyl, quinolinyl, indolyl, pyrimidinyl, imidazolyl, 1,2,4-triazolyl, tetrazolyl, etc., and examples of heteroatom-containing alicyclic groups are pyrrolidino, morpholino, piperazino, piperidino, etc.

“Hydrocarbyl” refers to univalent hydrocarbyl radicals containing 1 to about 30 carbon atoms, preferably 1 to about 24 carbon atoms, more preferably 1 to about 18 carbon atoms, most preferably about 1 to 12 carbon atoms, including branched, cyclic, saturated, and unsaturated species, such as alkyl groups, alkenyl groups, aryl groups, and the like. “Substituted hydrocarbyl” refers to hydrocarbyl substituted with one or more substituent groups, and the term “heteroatom-containing hydrocarbyl” refers to hydrocarbyl in which at least one carbon atom is replaced with heteroatom. Unless otherwise indicated, the term “hydrocarbyl” is to be interpreted as including substituted and/or heteroatom-containing hydrocarbyl moieties.

The term “hydrocarbylene” intends a divalent hydrocarbyl moiety containing 1 to about 24 carbon atoms, most preferably 1 to about 12 carbon atoms, including linear, branched, cyclic, saturated and unsaturated species, and the term “lower hydrocarbylene” intends a hydrocarbylene group of 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms. The term “substituted hydrocarbyl” refers to hydrocarbyl substituted with one or more substituent groups, and the terms “heteroatom-containing hydrocarbyl” and “heterohydrocarbyl” refer to hydrocarbyl is which at least one carbon atom is replaced with a heteroatom. Similarly, “substituted hydrocarbylene” refers to hydrocarbylene substituted with one or more substituent groups, and the terms “heteroatom-containing hydrocarbylene” and “heterohydrocarbylene” refer to hydrocarbylene in which at least one carbon atom is replaced with a heteroatom. Unless otherwise indicated, the terms “hydrocarbyl” and “hydrocarbylene” are to be interpreted as including substituted and/or heteroatom-containing hydrocarbyl and hydrocarbylene moieties, respectively. Oligomeric and polymeric hydrocarbylene moieties are also envisioned, including heteroatom-containing hydrocarbylenes such as poly(ethylene oxide) and substituted analogs thereof.

When a functional group is termed “protected” or “capped” as in an “end-capped” group, this means that the group is in modified form to preclude undesired reactions and/or promote a desired reaction. Suitable protecting groups for the compounds of the present disclosure will be recognized from the present application taking into account the level of skill in the art, and with reference to standard textbooks, such as Greene et al, Protective Groups in Organic Synthesis (New York: Wiley, 1991).

By “substituted” as in “substituted alkyl”, “substituted aryl” and the like, as alluded to in some of the aforementioned definitions, is meant that in the alkyl, aryl, or other moiety, at least one hydrogen atom bound to a carbon (or other) atom is replaced with one or more non-hydrogen substituents. Examples of such substituents include, without limitation: functional groups such as halo, hydroxyl, sulfhydryl, C₁-C₂₄ alkoxy, C₂-C₂₄ alkenyloxy, C₂-C₂₄ alkynyloxy, C₅-C₂₄ aryloxy, acyl (including C₂-C₂₄ alkylcarbonyl (—CO-alkyl) and (C₆-C₂₄ arylcarbonyl (—CO-aryl)), acyloxy (—O-acyl), C₂-C₂₄ alkoxycarbonyl (—(CO)—O-alkyl), C₆-C₂₄ aryloxycarbonyl (—(CO)—O-aryl), halocarbonyl (—CO)—X where X is halo), C₂-C₂₄ alkylcarbonato (—O—(CO)—O-alkyl), C₆-C₂₄ arylcarbonato (—O—(CO)—O-aryl), carboxy (—COOH), carboxylato (—COO—), carbamoyl (—(CO)—NH₂), mono-(C₁-C₂₄ alkyl)-substituted carbamoyl (—(CO)—NH(C₁-C₂₄ alkyl)), di-(C₁-C₂₄ alkyl)-substituted carbamoyl (13 (CO—N(C₁-C₂₄ alkyl)₂), mono-(C₆-C₂₄ aryl)-substituted carbamoyl (—(CO)—NH-aryl), di-((C₆-C₂₄ aryl)-substituted carbamoyl (—(CO)—N(aryl)₂), di-N-(C₁-C₂₄ alkyl), N-(C₆-C₂₄ aryl)-substituted carbamoyl, thiocarbamoyl (—(CS)—NH₂), carbamido (—NH—(CO)—NH₂), cyano(—C≡N), isocyano (—N⁺≡C⁻), cyanato (—OC≡N), isocyanato (—O—N⁺≡C⁻—), isothiocyanato (—SC═N), azido (—N═N⁺≡N⁻), formyl (—(CO)—H), thioformyl (—(CS)—H), amino (—NH₂), mono-(C₁-C₂₄ alkyl)-substituted amino, di-(C₁-C₂₄ alkyl)-substituted amino, mono-(C₅-C₂₄ aryl)-substituted amino, di-(C₅-C₂₄ aryl)-substituted amino, C₂-C₂₄ alkylamido (—NH—(CO)-alkyl), C₆-C₂₄ arylamido (—NH—(CO)-aryl), imino (—CR═NH wherein R=hydrogen, C₁-C₂₄ alkyl, C₅-C₂₄ aryl, C₆-C₂₄ alkaryl, C₆-C₂₄ aralkyl, etc.), alkylimino (—CR═N(alkyl), wherein R=hydrogen, C₁-C₂₄ alkyl, aryl, C₅-C₂₄ alkaryl, C₆-C₂₄ aralkyl, etc.), arylimino (—CR═N(aryl), wherein R=hydrogen, C₁-C₂₄ alkyl, C₅-C₂₄ aryl, C₆-C₂₄ alkaryl, C₆-C₂₄ aralkyl, etc.), nitro (—NO₂), nitroso (—NO), sulfo (—SO₂—OH), sulfonato (—SO₂—O—), C₁-C₂₄ alkylsulfanyl (—S-alkyl; also termed “alkylthio”), arylsulfanyl (—S-aryl; also termed “arylthio”), C₁-C₂₄ alkylsulfinyl (—(SO)-alkyl), C₅-C₂₄ arylsulfinyl (—(SO)-aryl), C₁-C₂₄ alkylsulfonyl (—SO₂-alkyl), C₅-C₂₄ arylsulfonyl (—SO₂-aryl), phosphono (—P(O)(OH)₂), phosphonato (—P(O)(O—)₂), phosphinato (—P(O)(O—)), phosho (—PO₂), and phosphino (—PH₂); and the hydrocarbyl moieties C₁-C₂₄ alkyl (preferably C₁-C₁₈ alkyl, more preferably C₁-C₁₂ alkyl, most preferably C₁-C₆ alkyl), C₂-C₂₄alkenyl (preferably C₂-C₁₈ alkenyl, more preferably C₂-C₁₂ alkenyl, most preferably C₂-C₆alkenyl), C₂-C₂₄ alkynyl (preferably C₂-C₁₈ alkynyl, more preferably C₂-C₁₂ alkynyl, most preferably C₂-C₆ alkynyl), C₅-C₂₄ aryl (preferably C₅-C₁₄ aryl), C₆-C₂₄ alkaryl (preferably C₆-C₁₈ alkaryl), and C₆-C₂₄ aralkyl (preferably C₆-C₁₈aralkyl).

In addition, the aforementioned functional groups may, if a particular group permits, be further substituted with one or more additional functional groups or with one or more hydrocarbyl moieties such as those specifically enumerated above. Analogously, the above-mentioned hydrocarbyl moieties may be further substituted with one or more functional groups or additional hydrocarbyl moieties such as those specifically enumerated.

The term “polymer” is used to refer to a chemical compound that comprises linked monomers, and that may be straight, branched, or crosslinked. The term also encompasses homopolymers, copolymers, terpolymers tetrapolymers and the like. Any polymers identified as containing more than one type of recurring unit, i.e., a copolymer, terpolymer, tetrapolymer or the like, are not intended to be limited with respect to configuration. That is, for example, copolymers herein may be block copolymers, alternating copolymers, random copolymers, terpolymers may be block terpolymers, random terpolymers, and the like. The term “oligomer” refers to a lower molecular weight, linear polymer that can participate in one or more reactions with itself or with other compounds, e.g., monomers and/or other oligomers, to form a higher molecular weight polymer structure.

When the term “substituted” appears prior to a list of possible substituted groups, it is intended that the term apply to every member of that group. For example, the phrase “substituted alkyl, alkenyl, and aryl” is to be interpreted as “substituted alkyl, substituted alkenyl, and substituted aryl”. Analogously, when the term “heteroatom-containing” appears prior to a list of possible heteroatom-containing groups, it is intended that the term apply to every member of that group. For example, the phrase “heteroatom-containing alkyl, alkenyl, and aryl” is to be interpreted as “heteroatom-containing alkyl, substituted alkenyl, and substituted aryl”.

“Optional” or “optionally” means that the subsequently described circumstance may or may not occur, so that the description includes instances where the circumstance occurs and instances where it does not. For example, the phrase “optionally substituted” means that a non-hydrogen substituent may or may not be present on a given atom, and, thus, the description includes structures wherein a non-hydrogen substituent is present and structures wherein a non-hydrogen substituent is not present. Similarly the phrase an “optionally present” bond as indicated by a dotted line in the chemical formulae herein means that a bond may or may not be present.

In one embodiment, then, the disclosure provides a curable resin composition by combining (i) an end-capped imide-terminated prepolymer with (ii) a photopolymerizable olefinic monomer, (iii) at least one photoinitiator, and (iv) a diamine, and optionally a pigment; in another embodiment, the disclosure provides a method for synthesizing the end-capped imide-terminated prepolymer. The curable resin composition is useful in a dual-cure method for forming a solid polymeric structure, such as in the context of an additive manufacturing process or other method of “3D” printing. The first step of the dual-cure method comprises irradiating the curable resin composition under conditions effective to polymerize the olefinic monomer and provide a polyolefin within a scaffold that comprises the prepolymer and the polyolefin, with the diamine physically trapped therein. In a second step, the photocured composition, i.e., the scaffold formed upon photopolymerization, is thermally treated under conditions effective to facilitate a transimidization reaction between the prepolymer and the diamine, thereby releasing the end caps of the prepolymer and providing a final polymeric structure that has superior mechanical properties and optimal surface characteristics.

The inventor found that when an phthalic anhydride-terminated oligomer (i.e. uncapped oligomer) are used to replace the prepolymer in the composition to form a resin composition, the mechanical properties of the product obtained by the resin composition are poor, and it may be as the resin composition thus formed cannot undergo the double curing described herein, and an expected product cannot be obtained.

2. The Photocurable Resin Composition

A. The Prepolymer:

The end-capped, imide-terminated prepolymer has the structure of formula (I),

wherein:

I. comprises an oligomeric hydrocarbylene moiety, and may be unsubstituted, substituted with one or more non-carbon, non-hydrogen substituents and/or functional groups as explained in section 1 of this detailed description, heteroatom-containing, or both substituted and heteroatom-containing. Accordingly, L can be alkylene, substituted alkylene, heteroalkylene, substituted alkylene, where any heteroatoms present are typically selected from nitrogen, oxygen, and sulfur, but most typically are oxygen atoms. An example of an alkylene “L” is an oligomers form of polyethylene, and an example of a heteroalkylene “L” is an oligomeric form of poly(ethylene oxide), such that L is

respectively.

wherein “n” represents the number of the monomer units contained within L. The number of monomer units is generally chosen to provide the prepolymer with a weight average molecular weight in the range of about 500 to about 5000, typically in the range of about 1000 to about 3000.

Ar is aryl, and includes, as explained in the preceding section, unsubstituted aryl, substituted aryl, heteroaryl, and substituted heteroaryl, wherein Ar may be monocyclic, bicyclic, or polycyclic, wherein, if bicyclic or polycyclic, the rings can be fused or linked. The two Ar moieties shown in the formula (I) may be the same or different, but are typically the same. When Ar is phenyl, the prepolymer has the structure of formula (II),

In formula (II), it can be seen that the two end groups are phthalimide moieties that are N-substituted with R² or R⁴, wherein R² and R⁴ are imide end-capping groups that are removed in the transimidization reaction. That is, R² and R⁴ are selected so that the following transimidization reaction can proceed upon heating (the reaction is shown in simplified form for illustrative purposes, with only one terminus of the prepolymer shown and a monofunctional R—NH₂ reactant instead of the diamine):

The imide end-capping groups R² and R⁴ are generally the same, to facilitate prepolymer synthesis as will be described infra. However, it will be appreciated that the disclosure does not require that R² and R⁴ be identical.

R¹ and R³ are divalent linking groups (also non-oligomeric linking groups), and r and q are 1. As with the end-capping groups R² and R⁴, it is preferred although not essential that r and q are the same and, when r and q are 1, that R¹ and R³ are the same as well.

In the present disclosure, it is preferred that the R¹ and R³ are divalent linking groups containing an acid anhydride structure, and it is more preferred that Ar—R¹ and Ar—R³ formed by the R¹ and R³ and adjacent aryl groups are selected from the groups provided by the following materials: pyromellitic dianhydride, 3,3′,4,4′-tetracarboxylic acid diphenyl ether dianhydride, 3,3′,4,4′-tetracarboxylic acid diphenyl ether dianhydride, 2,2′,3,3′-tetramethyl diphenyl ether dianhydride, 3,3′,4,4′-tetracarboxylic acid benzophenone dianhydride, 3,3′,4,4′-tetracarboxylic acid biphenyl dianhydride, 2,3,3′,4′-tetracarboxylic acid biphenyl dianhydride, 2,2′,3,3′-tetracarboxylic acid biphenyl dianhydride, 3,3′,4,4′-tetracarboxylic acid diphenyl sulfide dianhydride 2,3,3′,4′-tetracarboxylic acid diphenyl sulfide dianhydride, 2,2′,3,3′-tetracarboxylic acid diphenyl sulfide dianhydride.

In some embodiments, R¹ and R³ comprise phthalimide groups, such that the prepolymer has the structure of formula (III),

wherein s and t are independently selected from 0 and 1, and in a preferred embodiment s and t are the same. X and Y are independently selected from O, S, and lower alkylene (e.g., substituted or unsubstituted methylene, ethylene, n-propylene or n-butylene), although preferred X and Y are the same (preferably, both X and Y are O). When s and t are zero, the prepolymer of formula (III) has the structure of formula (IV),

Preferably, L contains one or more of polyethylene oxide chains, polypropylene oxide chains, polytetrahydrofuran chains and polyethylene chains; and more preferably, L contains one or more of unsubstituted polyethylene oxide chains, unsubstituted polypropylene oxide chains unsubstituted polytetrahydrofuran chains and unsubstituted polyethylene chains.

When L is poly(ethylene oxide), the prepolymer of formula (IV) has the structure shown in formula (V),

In formula (V), n is the number of ethylene oxide structural units.

When L is poly(ethylene), it will be appreciated that the prepolymer of formula (IV) has the structure of formula (VI),

In formula (VI), n is the number of ethylene structural units.

When L is a polyoxypropylene chain, it should be understood that the prepolymer represented by formula (IV) has a structure represented by formula (a1),

In formula (a1), n is the number of propylene oxide structural units,

when L is a polytetrahydrofuran chain, it should be understood that the prepolymer represented by formula (IV) has a structure represented by formula (a3),

In formula (a3), n is the number tetrahydrofuran structural units.

When s and t are 1 and X and Y are both O, the prepolymer the formula (III) has the structure of formula (VII),

wherein when L is polyethylene oxide chains, polyethylene chains, polypropylene oxide chains, or polytetrahydrofuran chains, the prepolymer of formula (VII) has the structure of formula (VIII) or formula (IX) or (a2) or formula (a4), respectively.

In formula (VIII), n is the number of ethylene oxide structural units.

In formula (IX), n is the number of ethylene structural units.

In formula (a2), n is the number of propylene oxide structural units.

In formula (a4), n is the number of tetrahydrofuran structural units.

The imide end-capping groups R² and R⁴, as explained above, are selected to enable a transimidization reaction to occur with the diamine. Any such end-capping groups may be advantageously used herein, provided that they facilitate transimidization and do not adversely interact with any components of the curable resin composition or have an adverse impact on the final product.

In some embodiments, the R² and R⁴ end-capping moieties are the same and are five- to six-membered cyclic groups containing 1 to 4, preferably 1 to 3, most preferably 1 or 2 heteroatoms, wherein at least one of the heteroatoms is a nitrogen atom and further wherein the ring nitrogen of the phthalimide group is directly bound to a carbon atom of the end capping moiety. Examples of such end-capping moieties include, without limitation, nitrogen-containing heterocyclic substituents such as pyridinyl, bipyridinyl, pyridazinyl, pyrimidinyl, bipyridaminyl, pyrazinyl, 1,3,5-triazinyl, 1,2,4-triazinyl, 1,2,3-triazinyl, pyrrolyl, 2H-pyrrolyl, 3H-pyrrolyl, pyrazolyl, 2H-imidazolyl, 1,2,3-triazolyl, 1,2,4-triazolyl, indolyl, 3H-indolyl, 1H-isoindolyl, cyclopenta(b)pyridinyl, indazolyl, quinolinyl, bisquinolinyl, isoquinolinyl, bisisoquinolinyl, cinnolinyl, quinazolinyl, naphthyridinyl, piperidinyl, piperazinyl, pyrrolidinyl, pyrazolidinyl, quinuclidinyl, imidazolidinyl, picolyliminyl, purinyl, benzimidazolyl, bisimidazolyl, phenazinyl, acridinyl, and carbazolyl. Preferred nitrogen heterocycles suitable as the imide end-capping groups are aryl, thus including pyrrolyl, imidazolyl, pyrazolyl, triazolyl, pyridinyl, pyrimidinyl, pyridazinyl, and pyrazinyl, as well as substituted analogs thereof.

In another preferred embodiment, the R² and R⁴ are each independently selected from five-membered or six-membered heterocyclic rings containing at least one nitrogen heteroatom; more preferably, the R² and R⁴ are each independently a heteroaromatic ring; more preferably, the R² and R⁴ are each independently selected from optionally substituted pyrrolyl, imidazolyl, pyrazolyl, triazolyl, pyridyl, pyrimidinyl, pyridazinyl and pyrazinyl; more preferably, the R² and R⁴ are each independently a pyrimidinyl group; and more preferably, the R² and R⁴ are

The representative prepolymers of the present disclosure in which R² and R⁴ are pyrimidinyl group are shown in the following formula (X) to formula (XIII), formula (b1), formula (b2), formula (b3), and formula (b4):

In formula (X), n is the number of ethylene oxide structural units.

In formula (XI), n is the number of ethylene structural units.

In formula (b1), n is the number of propylene oxide structural units.

In formula (b2), n is the number of tetrahydrofuran structural units.

Ideally, the prepolymer has a weight average molecular weight in the range of about 500 to about 5000, typically in the range of about 1000 to about 3000.

According to a particularly preferred embodiment, provided is a method for synthesizing a capped and imide-terminated prepolymer, the method comprising:

(a) contacting at least one o-aryl dicarboxylic anhydride having a structure of formula (A1) and at least one amine-terminated oligomer having a structure of formula (XVI) at a molar ratio of at least 2:1 under conditions effective to produce an o-aryl dicarboxylic anhydride-terminated oligomer as a reaction product, to obtain an o-aryl dicarboxylic anhydride-terminated oligomer; and

(b) mixing and reacting at least one amine-substituted reactant having a structure of formula (A2) with the o-aryl dicarboxylic anhydride-terminated oligomer at a molar ratio of at least 2:1 to obtain a capped and imide-terminated prepolymer;

NH₂—R⁴¹,   formula (A2)

in formula (A1), Ar is aryl group; and R³¹ is selected from monovalent linking groups containing an acid anhydride structure;

in formula (A2), R⁴¹ is selected from imide end-capping groups that can be removed in a transimidization reaction;

in formula (XVI), L contains unsubstituted, substituted, heteroatom-containing, or substituted and heteroatom-containing oligohydrocarbylene moieties.

In the foregoing preferred embodiments, more preferably, in the step (b), the reaction time is at least 12 hours;

in the foregoing preferred embodiments, more preferably, in the step (b), the temperature of the reaction is 100-250° C.; and more preferably 150-200° C.

In the foregoing preferred embodiments, in the formula (A1), Ar is preferably a monocyclic ring; more preferably, Ar does not contain a heteroatom; and particularly preferably, Ar is phenyl group.

In the aforementioned preferred embodiments, it is particularly preferred that the o-aryl dicarboxylic acid anhydride has a structure of formula (XVII),

wherein, in the formula (XVII) is 0 or 1, and Z is selected from O, S and lower alkylene;

more preferably, in the formula (XVII), u is 1 and Z is 0; and

more preferably, u is 0.

In the foregoing preferred embodiments, it is more preferable that the definition of the L group in the formula XVI) is as described above.

In the foregoing preferred embodiments, the amine-substituted reactant is an amine-substituted cyclic reactant;

preferably, the amine substituted reactant has a structure R⁷—NH₂, wherein R⁷ is a five-membered or six-membered heterocyclic ring containing at least one nitrogen heteroatom;

preferably, R⁷ is a heteroaromatic ring;

more preferably, R⁷ is selected from optionally substituted pyrrolyl, imidazolyl, pyrazolyl, triazolyl, pyridyl, pyrimidinyl, pyridazinyl and pyrazinyl;

it is further preferred that R⁷ is pyrimidinyl;

it is particularly preferred that R⁷ is

In a further embodiment, the disclosure provides a method for synthesizing the end-capped imide-terminated prepolymer wherein the synthetic method comprises:

(a) combining a diphthalic anhydride with an amine-terminated oligomer at a molar ratio of at least about 2:1 under conditions effective to give a phthalimide-terminated oligomer as a reaction product; and

(b) end-capping the phthalimide-terminated oligomer by admixing an aminosubstituted cyclic reactant with the phthalimide-terminated oligomer at a molar ratio of at least about 2:1 at an elevated temperature for a reaction time of at least about 12 hours.

In the best case, the prepolymer represents about 30 wt. % to about 70 wt. % of the composition; more preferably, the prepolymer represents about 40 wt. % to about 60 wt. % of the composition.

B. The Photopolymerizable Olefinic Monomer:

The photopolymerizable olefinic monomer serves as a reactive diluent and, upon irradiation, polymerizes and thereby facilitates formation of a stable, homogeneous network, or scaffold, which can then be thermally treated to form a final polymeric product. In some embodiments, the photopolymerizable olefinic monomer that serves as reactive diluent is an acrylate or methacrylate monomer. In other embodiments, the olefinic monomer comprises a vinyl ester such as vinyl acetate; vinyl chloride; vinyl alcohol; vinyl toluene; styrene; acrylonitrile; propene; butadiene; cyclohexene; or divinyl benzene. It is to be understood that the foregoing monomers are merely illustrative and not limiting; virtually any photopolymerizable olefinic monomer can be advantageously used in conjunction with the present disclosure.

In some embodiments, the photopolymerizable olefinic monomer, as noted above, is an acrylate or methacrylate monomer, which may be monofunctional, difunctional, or polyfunctional.

By “monofunctional” is meant that the acrylate or methacrylate monomer has one alkenyl functionality, with that functionality being the double bond contained within the acrylate moiety (i.e., the ═CH₂ at the carbon atom alpha to the carbonyl carbon), although the monomer may comprise one or more aryl moieties. The term “acrylate monomer” as used herein encompasses acrylates and methacrylates, i.e., esters of acrylic acid and methacrylic acid, respectively, as well as higher order acrylic acid esters such as ethyl acrylate, butyl acrylate, and the like. Methacrylates may in some embodiments be preferred relative to acrylates, however, insofar as the photopolymerization reaction (1) tends to proceed in a more controlled fashion with methacrylate monomers relative to acrylate monomers, and (2) may ultimately produce a product that has more desirable mechanical properties and surface finish.

In one embodiment, a photopolymerizable, monofunctional acrylate monomer has the structure of formula (XIV),

wherein R⁵ is H or methyl, such that the monomer is an acrylate or a methacrylate, respectively, and R⁶ is C₁˜C₃₆ hydrocarbyl, substituted C₁˜C₃₆ hydrocarbyl, heteroatom containing C₁˜C₃₆ hydrocarbyl, or substituted and heteroatom-containing C₁˜C₃₆ hydrocarbyl, and is typically C₁˜C₂₄ hydrocarbyl, substituted C₁˜C₂₄ hydrocarbyl, heteroatom-containing C₁˜C₂₄ hydrocarbyl, or substituted and heteroatom-containing C₁˜C₂₄ hydrocarbyl, such as C₂˜C₁₆ hydrocarbyl, substituted C₂˜C₁₆ hydrocarbyl, heteroatom-containing C₂˜C₁₆ hydrocarbyl, or substituted and heteroatom-containing C₁˜C₁₆hydrocarbyl, C₄˜C₁₂ hydrocarbyl, substituted C₄˜C₁₂, hydrocarbyl, heteroatom-containing C₄˜C₁₂ hydrocarbyl, or substituted and heteroatom-containing C₄˜C₁₂ hydrocarbyl. Within the aforementioned categories, R⁵ may be, by way of example, C₁˜C₃₆ alkyl, substituted C₁˜C₃₆ alkyl, heteroatom-containing C₁˜C₃₆ alkyl, or substituted and heteroatom-containing C₁˜C₃₆ alkyl, and typically C₁˜C₂₄ alkyl, substituted C₁˜C₂₄ alkyl, heteroatom-containing C₁∫C₂₄ alkyl, or substituted and heteroatom-containing C₁˜C₂₄ alkyl, such as C₂˜C₁₆ alkyl, substituted C₂˜C₁₆ alkyl, heteroatom-containing C₂˜C₁₆ alkyl, or substituted and heteroatom-containing C₂˜C₁₆ alkyl, or C₄˜C₁₂ alkyl, substituted C₄˜C₁₂ alkyl, heteroatom-containing C₄˜C₁₂ alkyl, or substituted and heteroatom containing C₄˜C₁₂ alkyl. As noted above, the R⁵ moiety can also be aryl, including unsubstituted aryl, substituted aryl, heteroaryl, substituted heteroaryl, unsubstituted aralkyl, substituted aralkyl, heteroaralkyl, substituted heteroaralkyl, such as C₅˜C₃₆ unsubstituted aryl, substituted C₅˜C₃₆ aryl, substituted C₂˜C₃₆ heteroaryl, substituted C₂˜C₃₆ heteroaryl, unsubstituted C₆˜C₃₆ aralkyl, substituted C₆˜C₃₆ aralkyl, C₃˜C₃₆ heteroaralkyl, substituted C₃˜C₃₆ heteroaralkyl, typically C₅˜C₂₄ unsubstituted aryl, substituted C₅˜C₂₄ aryl, C₂˜C₂₄ heteroaryl, substituted C₂˜C₂₄ heteroaryl, unsubstituted C₆˜C₂₄ aralkyl, substituted C₆˜C₂₄ heteroaralkyl, C₃˜C₂₄ heteroaralkyl, substituted C₃˜C₂₄ heteroaralkyl, such as unsubstituted (C₅˜C₁₆ aryl, substituted C₅˜C₁₆ aryl, C₂˜C₁₆ heteroaryl, substituted C₂˜C₁₆ heteroaryl, unsubstituted C₆˜C₁₆ aralkyl, substituted C₆˜C₁₆ aralkyl, C₃˜C₁₆ heteroaralkyl, substituted C₃˜C₁₆ heteroaralkyl, C₅˜C₁₂ unsubstituted aryl, substituted C₅˜C₁₂ aryl C₂˜C₁₂ heteroaryl, substituted C₂˜C₁₂ heteroaryl, unsubstituted C₆˜C₁₂ aralkyl, substituted C₆˜C₁₂ aralkyl, C₃˜₁₂ heteroaralkyl, substituted C₃˜C₁₂ heteroaralkyl, Any heteroatoms are usually N or O, and aryl groups are usually, but not necessarily, monocyclic; fused and linked bicyclic or tricyclic groups are also contemplated.

In some embodiments, R⁶ comprises a C₆˜C₃₆ alicyclic moiety, typically a bridged (bicyclic or polycyclic) C₆˜C₃₆ alicyclic moiety, and may be substituted and/or heteroatom containing. R⁶ thus includes optionally substituted and/or heteroatom-containing C₆˜C₂₄ alicyclic and C₆˜C₁₆ alicyclic groups. Non-limiting examples of such groups suitable as R⁵ include adamantyl, 2-methyl-2-adamantyl, 2-ethyl-2-adamantyl, 5-hydroxy-2-methyl-2-adamantyl, 5-hydroxy-2-ethyl-2-adamantyl, 1-methyl-1-adamantylethyl, 2-methyl-2 -norbornyl, 2-ethyl-2-norbornyl, 1,2,7,7-tetramethyl-2-norbornyl, isobornyl, and the like.

Specific examples of photocurable monofunctional acrylate and methacrylate monomers thus include, without limitation, isobornyl acrylate, isobornyl methacrylate, adamantyl acrylate, adamantyl methacrylate, isodecyl acrylate, isodecyl methacrylate, lauryl acrylate, lauryl methacrylate, 3,3,5-trimethylcyclohexane acrylate, 3,3,5-trimethylcyclohexane methacrylate, (2-(2-ethoxyethoxy) ethyl acrylate, (2-(2-ethoxyethoxy) ethyl methacrylate, cyclic trimethylolpropane formal acrylate, cyclic trimethylolpropane formal methacrylate, tetrahydrofurfuryl acrylate, tetrahydrofurfuryl methacrylate, tridecyl acrylate, tridecyl methacrylate, 2-phenoxy ethyl acrylate, and 2-phenoxy ethyl methacrylate. Other examples will be apparent to those of ordinary skill in the art or can be found in the pertinent texts and literature. See, e.g., U.S. Pat. No. 7,041,846 to Watanabe et al, the disclosure of which is incorporated herein with regard to monofunctional acrylate and methacrylate monomers.

Difunctional acrylate and methacrylate moieties useful in conjunction with the present methods and compositions include tripropyleneglycol diacrylate, 1,6-hexanediol diacrylate, tricyclodecane dimethanol diacrylate, diethyleneglycol dimethacrylate, dipropyleneglycol diacrylate, difunctional glycol acrylate, ethoxylated bisphenol A diacrylates, propyoxylated neopentylglycol diacrylates, neopentylglycol diacrylate, and ethyleneglycol dimethacrylate, while examples of polyfunctional acrylates and methacrylates suitable for use herein include trimethylpropane triacrylate, trimethylpropane trimethacrylate, ethoxylated trimethylpropane triacrylates, propoxylated glyceryl triacrylates, tris-(2-hydroxyethyl) isocyanurate triacrylate, pentaerythritol triacrylate, ethoxylated pentaerythritol tetraacrylates, trimethylolpropane triacrylate (TMPTA), di(trimethylolpropane) tetraacrylate, dipentaerythritol hexaacrylate, and dipentaerythritol hexaacrylate.

Preferably, the at least one photopolymerizable olefinic monomer represents about 25 wt. % to about 75 wt. % of the composition, more preferably, the at least one photopolymerizable olefinic monomer represents about 25 wt. % to about 65 wt. % of the composition, still further preferably, the at least one photopolymerizable olefinic monomer represents about 30 wt. % to about 60 wt. % of the composition, more preferably, the at least one photopolymerizable olefinic monomer represents about 35 wt. % to about 55 wt. % of the composition.

C. Polymerization Initiators:

Another component of the curable resin composition is a photopolymerization initiator, or “photoinitiator”. As the initial step in the dual-cure process requires photopolymerization of the olefinic monomer, the curable resin composition comprises at least one photoinitiator, i.e., a free radical photoinitiator. The free radical photoinitiator may be, by way of illustration and not limitation: an acylphosphine oxide, such as 2,4,6-trimethylbenzoylethoxyphenylphosphine oxide) (TEPO), diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO), bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, or the like; an oc-hydroxy ketone, such as 2-hydroxy-2-methyl-1-phenyl acetone, 1-hydroxy-cyclohexyl benzophenone, 2-hydroxy-2-methyl-1-p-hydroxyethylether phenyl acetone, etc.; a diarylketone such as benzophenone, 2,2-dimethoxy-2-phenylacetophenone (DMPA), benzoyl peroxide; azobisisobutyronitrile (AIBN); or an oxime ester such as those available under the Irgacure tradename from BASF.

Preferably, the at least one photoinitiator represents about 0.1 wt. % to about 5 wt. % of the composition; more preferably, the at least one photoinitiator represents about 1 wt. % to about 3 wt. % of the composition.

D. The Diamine:

The diamine reactant, or “chain extender” is selected to undergo transimidization with the imide end capped prepolymer upon thermal treatment of the photocured resin composition. The diamine has the structure of formula (XV),

H₂N—L¹—NH₂   formula (XV)

wherein L¹ is C₂˜C₁₄ hydrocarbylene, including unsubstituted, substituted, heteroatom-containing, and substituted heteroatom-containing C₂˜C₁₄ hydrocarbylene. Typically, L¹ is an unsubstituted alkylene group, such that the diamine is 1,3-propanediamine, 1,2-propanediamine, 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, 1,2-cyclohexanediamine, 1,4-cyclohexanediamine, or 4,4′-diaminodicyclohexyl methane.

Preferably, the diamine represents about 1 wt. % to about 25 wt. % of the composition; more preferably, the diamine represents about 1 wt. % to about 15 wt. % of the composition; still further preferably, the diamine represents about 1 wt. % to about 10 wt. % of the composition; particularly preferably, the diamine represents about 1 wt. % to about 5 wt. % of the composition.

Additives:

The curable resin composition can include any of various additives to facilitate the curing processes and provide the final product with one or more advantageous properties. Such additives include, by way of example: tougheners; fillers; stabilizers; non-reactive light absorbers; polymerization inhibitors; colorants including dyes and pigments; thickening agent; detectable compounds (e.g., radioactive or luminescent compounds); metal powders or fibers or other conductive materials; semiconductive particulates or fibers; magnetic materials; flame retardants; and the like. Preferred additives are those described in U.S. Pat. No. 9,598,608 to Rolland et al, incorporated by reference herein.

The pigments described herein are non-reactive pigments or dyes that can absorb light, particularly ultraviolet light, and can include, for example, carbon black, titanium dioxide, an organic ultraviolet light absorber, and the like. Among them, the organic UV absorber can be hydroxybenzophenone, hydroxyphenyl benzotriazole, oxanilide, benzophenone, thioxanthone, hydroxyphenyl triazine and/or benzotriazole UV light absorbers, and the like.

Preferably, the pigments accounts for 0% to 5% by weight of the composition, more preferably, the pigment accounts for 0.1% to 3% by weight of the composition.

3. New Compositions of Matter:

In one embodiment, the disclosure provides a curable resin composition as a new composition of matter, wherein the composition comprises: (i) an end-capped, imide-terminated prepolymer; (ii) at least one photopolymerizable olefinic monomer; (iii) at least one photoinitiator and (iv) a diamine, wherein each of the components are as defined in A through E above.

In another embodiment, the disclosure provides a photocured composition prepared by irradiating the curable resin composition with actinic radiation of a wavelength effective to cure the photopolymerizable olefinic monomer.

In an additional embodiment, the disclosure provides a solid composition of matter prepared by: (a) irradiating the curable resin composition with actinic radiation of a wavelength effective to cure the photopolymerizable olefinic monomer; and (b) thermally treating the photocured composition provided in (a) with heat under conditions to facilitate a transimidization reaction between the end-capped, imide-terminated prepolymer and the diamine.

4. Other Embodiments:

The disclosure additionally encompasses other embodiments, wherein a prepolymer other than an end-capped, imide-terminated prepolymer is employed. The process for forming a 3D specimen from such other prepolymers is analogous to that described above with regard to the end-capped, imide-terminated prepolymer. That is, the selected prepolymer is combined with at least one photopolymerizable olefinic monomer, at least one photoinitiator, and a diamine, to form a curable resin composition. The composition is irradiated under conditions effective to polymerize the at least one photopolymerizable olefinic monomer, forming a scaffold that comprises the prepolymer and the polyolefin with the diamine physically trapped therein. The irradiated scaffold is then thermally treated at a temperature effective to allow a cross-linking reaction to occur between the prepolymer and the diamine, providing the solid polymeric structure.

In some embodiments, prior to irradiation, the curable resin composition is added to a construction area which corresponds in size to a predetermined shape and size of a 3D structure to be manufactured.

In other embodiments, the method is implemented in the context of an improved additive manufacturing process that includes computer-controlled continuous formation of layers having dimensions corresponding to a 3D digital image, the improvement comprises forming layers by the following steps:

(a) providing an initial curable layer on a substrate, wherein the initial curable layer contains a curable resin composition prepared by mixing a capped and imide-terminated prepolymer, a photopolymerizable ethylenic monomer, at least one photoinitiator, and a diamine;

(b) irradiating the initial layer under conditions of effective polymerization of the photopolymerizable ethylenic monomer to obtain a first scaffold layer; wherein preferably, the first scaffold layer contains a prepolymer and a polyolefin, and has a diamine physically trapped therein;

(c) repeating the step (a) to provide an additional layer on the first scaffold layer;

(d) irradiating the additional layer under conditions effective to polymerize the photopolymerizable ethylenic monomer and provide an additional scaffold layer;

(e) repeating steps (c) and (d) until the formation of the 3D object is completed; and

(f) subjecting the 3D object at a temperature that effectively causes a covalent reaction between the prepolymer and the diamine.

In the present disclosure, with regard to the methods in which dual curing is performed by using the curable composition have the following preferred situations:

first, in each method in which dual curing is performed by using the curable composition, the irradiation is performed using actinic radiation; and more preferably, the actinic radiation is ultraviolet radiation.

Then, in each method in which dual curing is performed by using the curable composition, the actinic radiation has a wavelength selected to promote the polymerization of the photopolymerizable ethylenic monomer; more preferably, the wavelength corresponds to the wavelength of ultraviolet light; further preferably, the wavelength is 350˜415 nm; and particularly preferably, the wavelength is 405±5 nm, 385±5 nm, 395±5 nm, 365±5 nm or 355±5 nm.

And, in each method in which dual curing is performed by using the curable composition, it is preferable to apply ultraviolet radiation at an intensity of 13,000 to 15,000 m/cm².

And, in each method in which dual curing is performed by using the curable composition, it is preferable that the heat treatment is performed in a temperature range of 75° C. to 300° C.

In yet another embodiment, the present disclosure provides a method for forming a three-dimensional object layer in an additive manufacturing process,

the method comprises:

(a) mixing (i) a capped and imide-terminated prepolymer and (ii) a photopolymerizable ethylenic monomer, (iii) at least one photoinitiator, (iv) a diamine, and optionally (v) a pigment to form a curable resin composition;

(b) providing the curable resin composition on a substrate to form a layer; and

(c) irradiating the layer under conditions of polymerizing the photopolymerizable ethylenic monomer.

In yet another embodiment, the present disclosure provides a method for forming a three-dimensional object using an additive manufacturing process, the method comprises continuously forming a layer having a size corresponding to a three-dimensional digital image on a substrate through computer control, the improvement lies in including the formation of a layer by the following steps:

(a) provide an initial curable layer on a substrate, wherein the initial curable layer contains a curable resin composition prepared by mixing a capped and imide-terminated prepolymer, a photopolymerizable ethylenic monomer, at least one photoinitiator, a diamine, and optionally a pigment;

(b) irradiating the initial curable layer under conditions of polymerizing the photopolymerizable ethylenic monomer to obtain a first scaffold layer;

(c) repeating the step (a) to provide an additional layer on the first scaffold layer;

(d) irradiating the additional layer under conditions of polymerizing the photopolymerizable ethylenic monomer;

(e) repeating steps (c) and (d) until the formation of a three-dimensional object is completed; and

(f) subjecting the three-dimensional object at a temperature that causes a transimidization reaction between the prepolymer and the diamine.

In yet another embodiment, the present disclosure provides an article prepared by the method described in any of the foregoing embodiments of the present disclosure; and preferably, the article is a three-dimensional article.

In yet another embodiment, the present disclosure provides use of the prepolymer described in any of the foregoing embodiments and the curable resin composition described in any of the foregoing embodiments in forming an article; preferably, the prepolymer and the curable resin composition are additively manufactured to form an article; and it is particularly preferred that the article is a three-dimensional article.

It should be understood that although the present disclosure has been described in conjunction with a number of specific embodiments, the foregoing description and the following examples are intended to illustrate rather than limit the scope of the present disclosure.

Embodiment 1 Synthesis of N-(2-Pyrimidyl)phthalimide-Terminated Imide Prepolymer

100.00 g (0.05 mol) of melted anhydrous amine-terminated polyethylene glycol (molecular weight 2,000 g/mol) was added into a 500 mL four-neck flask equipped with an overhead stirrer, a nitrogen inlet, a thermometer and a reverse Dean-Stark trap with a condenser.

Then, 31.02 g (0.10 mol) of 4,4′-oxydiphthalic anhydride was added into the flask, followed by addition of 39 mL cyclohexyl pyrrolidinone. The solution was stirred for 4 hours at 25° C. and an increase in the solution viscosity was observed. The temperature was then increased to 175° C. and stirred for an additional 12 hours. 9.51 g (0.10 mol) of 2-aminopyrimidine was then added into the solution and the solution was stirred at 175° C. for an additional 12 hours. The viscous liquid was then cooled and poured as the final product (The number average molecular weight is 2,800).

The two-step reaction is illustrated in scheme 1:

Embodiment 2 Specimen Formation and Testing Using the Phthalimide-Terminated Imide Prepolymer

(a) General Procedures:

The prepolymer synthesized in embodiment 1 was polymerized and cured to form 3D structures as described infra. Tensile properties were evaluated in accordance with the following ISO standards: ISO 37 (2017) Rubber, Vulcanized or Thermoplastic-Determination of tensile stress-strain properties for non-rigid materials; and ISO 527 (2017) Plastics-Determination of tensile properties for rigid materials (International Organization for Standardization, BIBC II Chemin de Blandonnet 8, CP 401, 1214 Vernier, Geneva, Switzerland).

A tensile sample is loaded on the INSTRON 3366 electronic universal testing machine (purchased from Instron (Shanghai) Testing Equipment Trading Co., Ltd.), and oriented vertically and parallel to the direction of testing. Cast samples were fully cured using an LED UV chamber (UV wave length=405±5 nm, intensity=130×10² μm/cm² to 150×10² μm/cm²) for 60 seconds. Then, the samples were thermally treated in a convection oven, with specific treatment conditions indicated below. Table 1 indicates the types of tensile specimens tested, general material properties and the associated strain rate.

Measured dogbone samples that do not rupture in the central rectangular section were excluded. Samples that broke in the grips or prior to testing were not representative of the anticipated failure modes and were also excluded from the data.

In order to ensure that the strain rate of the sample was sufficient to capture deformation, the sample was subjected to a tensile fracture test for 30 seconds to 5 minutes.

Depending on the type of the material and pursuant to ISO 37 and ISO 527, Young's modulus (the slope of the stress-strain diagram at 0.05%˜0.25% strain), tensile strength at break, tensile strength at yield, percentage of elongation at break, the percentage of elongation at yield, and ultimate tensile strength were measured.

For elastomeric materials having a high elongation at break, a high-speed strain rate is required to break it in the usual range of the specified test. For rigid materials, the ISO standard recommends a modulus of elasticity test rate of 1 mm/min to ensure the lowest strain-at-break will occur within 5 minutes.

TABLE 1 material Material Specimen type Standards type strain rate remarks non-rigid ISO 37 1A 500 mm/min — rigid ISO 527-2 5A  10 mm/min — rigid ISO 527-2 5A  1 mm/min for Young's Modulus

(II) Specimen Formation and Evaluation:

The UV-curable N-(2-pyrimidyl)phthalimide-terminated imide prepolymer prepared in embodiment 1 was thoroughly mixed with isobornyl methacrylate, trimethylolpropane trimethacrylate (TMPTMA), and TPO, using an overhead stirrer, to obtain a homogeneous resin.

The resin was cast into a 150 mm×100 mm×4 mm mold and UV cured for 1 minute. Then, the specimen was subjected to a thermal cure by heating at 100° C. for 1 hour, followed by heating at 220° C. for 4 hours. The cured elastomeric sheet so formed was cut into rectangular bars with dimensions of 150 mm×100 mm×4 mm. The individual specimens were tested following ISO 527 on a universal testing machine from NCS for mechanical properties as described above. The average tensile strength (MPa) and elongation at break (%) are provided in table 2, along with the weight percent of each component in the transimidization reaction mixture.

TABLE 2 component weight % N-(2-pyrimidyl)phthalimide-terminated imide 50.0 prepolymer isobomyl methacrylate 35.0 TMPTMA 10.2 TPO 1.0 4,4′-diaminodicyclohexyl methane 3.8 tensile strength (MPa) 16.4 elongation at break (%) 218

Embodiment 3

This embodiment was carried out using a method similar to that of embodiment 1, except that the raw material anhydrous amine-terminated polyethylene glycol was not used in this embodiment, specifically:

31.02 g (0.10 mol) of 4,4′-oxydiphthalic anhydride was added to a 500 mL four-necked flask equipped with an overhead stirrer, a nitrogen inlet, a thermometer, and a trans-Dean-Stark (Dean-Stark) water trap with a condenser, then 300 mL of anhydrous NMP was added and stirred well until 4-oxydiphthalic anhydride was completely dissolved. Then 39 mL N-cyclohexylpyrrolidone (CHP) was added, and the temperature was increased to 175° C. The reaction solution was then refluxed at 175° C. for 12 hours. 9.51 g (0.10 mol) of 2-aminopyrimidine was added to the solution, and the solution was stirred at 175° C. for another 12 hours. Finally, the solvent of the reaction solution was distilled, and a final product (having a number average molecular weight of 464.4) was obtained.

Embodiment 4

This embodiment was carried out using a method similar to that of embodiment 1, except that in this embodiment the same molar amount of 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) was used to replace 4,4′-oxydiphthalic anhydride of embodiment 1, specifically:

100.00 g (0.05 mol) of molten anhydrous amine-terminated polyethylene glycol (molecular weight 2000 g/mol) was added to a 500 mL four-necked flask equipped with an overhead stirrer, a nitrogen inlet, a thermometer, and a trans-Dean-Stark (Dean-Stark) water trap with a condenser.

Then, 0.10 mol of BPDA was added to the flask, followed by 39 mL of N-cyclohexylpyrrolidone (CHP). The solution was stirred at 25° C. for 4 hours, and an increase in the viscosity of the solution was observed. Then, the temperature was increased to 175° C. and stirred for another 12 hours. Next, 9.51 g (0.01 mol) of 2-aminopyrimidine was added to the solution, and the solution was stirred at 175° C. for another 12 hours. Finally, the viscous liquid is cooled and poured out as a final product (having a number average molecular weight of 2738).

Embodiment 5

This embodiment was carried out using a method similar to that of embodiment 1, except that in this embodiment, 0.05 mol of anhydrous amine-terminated polypropylene glycol (molecular weight 650 g/mol) was used to replace the anhydrous amine-terminated polyethylene glycol in embodiment 1, specifically:

0.05 mol of molten anhydrous amine-terminated polypropylene glycol (molecular weight 650 g/mol) to a 500 mL four-necked flask equipped with an overhead stirrer, a nitrogen inlet, a thermometer, and a trans-Dean-Stark (Dean-Stark) water trap with a condenser.

Then, 0.10 mol of 4,4′-oxydiphthalic anhydride was added to the flask, followed by 39 mL N-cyclohexylpyrrolidone (CHP). The solution was stirred at 25° C. for 4 hours, and an increase in the viscosity of the solution was observed. Then, the temperature was increased to 175° C. and stirred for another 12 hours. Next, 0.10 mol of 2-aminopyrimidine was added to the solution, and the solution was stirred at 175° C. for another 12 hours. Finally, the viscous liquid is cooled and poured out as a final product (number average molecular weight 1,450).

Embodiment 6

This embodiment was carried out using a method similar to that of embodiment 1, except that 0.05 mole of anhydrous amine-terminated polytetrahydrofuran (molecular weight 2,000 g/mol) was used to replace the anhydrous amine-terminated polyethylene glycol in embodiment 1,

specifically:

0.05 mol of molten anhydrous amine-terminated polytetrahydrofuran (molecular weight 2,000 g/mol) was added to a 500 mL four-necked flask equipped with an overhead stirrer, a nitrogen inlet, a thermometer, and a trans-Dean-Stark (Dean-Stark) water trap with a condenser.

Then, 0.10 mol of 4,4′-oxydiphthalic anhydride was added to the flask, followed by 39 mL of N-cyclohexylpyrrolidine (CHP). The solution was stirred at 25° C. for 4 hours, and an increase in the viscosity of the solution was observed. Then, the temperature was increased to 175° C. and stirred for another 12 hours. Next, 0.10 mol of 2-aminopyrimidine was added to the solution, and the solution was stirred at 1,275° C. for another 12 hours. Finally, the viscous liquid is cooled and poured out as a final product (number average molecular weight 2,800).

Embodiment 7

This embodiment was carried out using a method similar to that of embodiment 2, except that the components in the resin composition formulation are different from those in embodiment 2. specifically, as shown in table 3 below, the UV curable colorant JC-201 was purchased from Dongguan Jiacai Industrial Co., Ltd. The test was performed using the same test method as in embodiment 2, and the obtained test results are shown in table 3.

TABLE 3 prepolymer source Embodi- Embodi- Embodi- Embodi- ment 3 ment 4 ment 5 ment 6 component weight % prepolymer 50.0 50.0 50.0 50.0 isobornyl methacrylate 116.1 35.0 31.3 35.1 TMPTMA 10.2 10.2 10.2 10.2 TPO 1.0 1.0 1.0 1.0 4,4′- 22.6 3.8 7.5 3.7 diaminodicyclohexyl methane UV light-curing 0.1 / / / colorant JC-201 tensile strength (MPa) 80 18 48 17 elongation at break (%) 25 190 65 250

Embodiment 8

This embodiment was carried out using a method similar to that of embodiment 2. except that the contents of the components in the resin composition formulation are different from those of embodiment 2, specifically, as shown in table 4. In addition, the same test method as in embodiment 2 was used for testing, and the obtained test results are shown in table 4.

TABLE 4 weight % Embodi- Embodi- Embodi- Embodi- component ment 8-1 ment 8-2 ment 8-3 ment 8-4 prepolymer 40.0 60.0 50.0 30.0 isobornyl 45.8 24.3 35.0 56.5 methacrylate TMPTMA 10.2 10.2 10.2 10.2 TPO 1.0 1.0 1.0 1.0 4,4′- 3.0 4.5 3.8 2.3 diaminodicyclohexyl methane tensile strength (MPa) 18 35 16.4 8.3 elongation at break 181 267 218 130 (%) 

1. An end-capped and imide-terminated prepolymer, wherein the repolymer has structural of formula (I):

wherein: L comprises an oligomeric hydrocarbylene moiety that is unsubstituted, substituted, heteroatom-containing, or substituted and heteroatom-containing; Ar is aryl; R¹ and R³ may be the same or different and are divalent linking group; q and r are both 1; and R² and R⁴ are imide end-capping groups that can be removed in a transimidization reaction.
 2. The prepolymer according to claim 1, wherein, the Ar is a monocyclic, preferably, Ar does not contain a heteroatom.
 3. The prepolymer according to claim 1, wherein, the repolymer has structural of formula (II):

wherein; q and r are both 1; preferably, R¹ and R³ are the same; more preferably, R² and R⁴ are the same.
 4. The prepolymer according to claim 1, wherein, the repolymer has structural of formula (III):

wherein: s and t are independently selected from 0 and 1, X and Y are independently selected from O, S, and lower alkylene; preferably, both X and Y are O; preferably, both s and t are
 0. 5. The prepolymer according to claim 1, wherein, the repolymer is one or two selected from a repolymer having a structural of formula (IV) and a repolymer having a structural of formula (VII):


6. The prepolymer according to claim 1, wherein, L contains one or more of polyethylene oxide chains, polypropylene oxide chains, polytetrahydrofuran chains and polyethylene chains; and preferably, L contains one or more of unsubstituted polyethylene oxide chains, unsubstituted polypropylene oxide chains, unsubstituted polytetrahydrofuran chains and unsubstituted polyethylene chains.
 7. The prepolymer according to claim 1, wherein, the repolymer is one or two selected from a repolymer having a structural of formula (V), a repolymer having a structural of formula (VI), a repolymer having a structural of formula (VIII), a repolymer having a structural of formula (IX), a repolymer having a structural of formula (a1), a repolymer having a structural of formula (a2), a repolymer having a structural of formula (a3), and a repolymer having a structural of formula (a4):

in formula (V), n is the number of ethylene oxide structural units.

in formula (VI), n is the number of ethylene structural units.

in formula (VIII), n is the number of ethylene oxide structural units,

in formula (IX), n is the number of ethylene structural units,

in formula (a1), n is the number of propylene oxide structural units,

in formula (a2), n is the number of propylene oxide structural units,

in formula (a3), n is the number of tetrahydrofuran structural units,

in formula (a4), n is the number of tetrahydrofuran structural units.
 8. The prepolymer according to claim 1, wherein, the R² and R⁴ are each independently selected from five-membered or six-membered heterocyclic rings containing, at least one nitrogen heteroatom; more preferably, the R² and R⁴ are each independently a heteroaromatic ring; more preferably, the R² and R⁴ are each independently selected from optionally substituted pyrrolyl, imidazolyl, pyrazolyl, triazolyl, pyridyl, pyrimidinyl, pyridazinyl and pyrazinyl; more preferably, the R² and R⁴ are each independently a pyrimidinyl group; and more preferably, the R² and R⁴ are


9. The prepolymer according to claim 7, wherein, the repolymer is one or two selected from a repolymer having a structural of formula (X), a repolymer having a structural of formula (XI), a repolymer having a structural of formula (b1), a repolymer having a structural of formula (b2):

in formula (X), n is the number of ethylene oxide structural units,

in formula (XI), n is the number of ethylene structural units,

in formula (b1), n is the number of propylene oxide, structural units,

in formula (b2), n is the number of tetrahydrofuran structural units.
 10. The prepolymer according to claim 1, wherein, the prepolymer has a weight average molecular weight in the range of about 500 to about 5000, preferably, the prepolymer has a weight average molecular weight in the range of about 1000 to about
 3000. 11. A method for synthesizing a capped and imide-terminated prepolymer, wherein the method comprising: (a) contacting at least one o-aryl dicarboxylic anhydride having a structure of formula (A1) and at least one amine-terminated oligomer having a structure of formula (XVI) at a molar ratio of at least 2:1 under conditions effective to produce an o-aryl dicarboxylic anhydride-terminated oligomer as a reaction product, to obtain an o-aryl dicarboxylic anhydride-terminated oligomer; and (b) mixing and reacting at least one amine-substituted reactant having a structure of formula (A2) with the o-aryl dicarboxylic anhydride-terminated oligomer at a molar ratio of at least 2:1 to obtain the capped and imide-terminated prepolymer;

NH₂—R⁴¹,   formula (A2) in formula (A1), Ar is aryl group; and R³¹ is selected from monovalent linking groups containing an acid anhydride structure; in formula (A2), R⁴¹ is selected from imide end-capping groups that can be removed in a transimidization reaction; in formula (XVI), L contains unsubstituted, substituted, heteroatom-containing, or substituted and heteroatom-containing oligohydrocarbylene moieties.
 12. The method according to claim 11, wherein, the Ar is a monocyclic ring; preferably, Ar does not contain a heteroatom; and more preferably, Ar is phenyl group.
 13. The method according to claim 11, wherein, the o-aryl dicarboxylic acid anhydride has a structure of formula (XVII):

wherein, in formula; (XVII), u is 0 or 1, and Z is selected from O, S and lower alkylene; more preferably, in formula (XVII), u is 1 and Z is O; and more, preferably, u is
 0. 14. The method according to claim 11, wherein, L contains one or more of polyethylene oxide chains, polypropylene oxide chains, polytetrahydrofuran chains and polyethylene chains: and preferably, L contains one or more of unsubstituted polyethylene oxide chains, unsubstituted polypropylene oxide chains, unsubstituted polytetrahydrofuran chains and unsubstituted polyethylene chains.
 15. The method according to claim 11, wherein, the amine-substituted reactant is an amine-substituted cyclic reactant preferably, the amine substituted reactant has a structure R⁷—NH₂, wherein R⁷ is a five-membered or six-membered heterocyclic ring containing at least one nitrogen heteroatom; preferably, R⁷ is a heteroaromatic ring; more preferably, R⁷ is selected from optionally substituted pyrrolyl, imidazolyl, pyrazolyl, triazolyl, pyridyl, pyrimidinyl, pyridazinyl and pyrazinyl, it is further preferred that R⁷ is pyrimidinyl;

particularly preferably, R⁷ is
 16. The method according to claim 11, wherein the synthetic method comprises: (a) combining a diphthalic anhydride with an amine-terminated oligomer at a molar ratio of at least about 2:1 under conditions effective to give a phthalimide-terminated oligomer as a reaction product; and (b) end-capping the phthalimide-terminated oligomer by admixing an aminosubstituted cyclic reactant with the phthalimide-terminated oligomer at a molar ratio of at least about 2:1 at an elevated temperature for a reaction time of at least about 12 hours.
 17. The capped and imide-terminated prepolymer prepared by the method of claim
 11. 18. A curable resin composition, wherein the resin composition contains an end-capped, imide-terminated prepolymer, at least one photopolymerizable olefinic monomer, at least one photoinitiator, and a diamine, and optionally a pigment, the prepolymer is the prepolymer described in claim
 1. 19. The composition according to claim 18, wherein, the prepolymer accounts for 30% to 70% by weight of the composition, more preferably, the prepolymer accounts for 40% to 60% by weight of the composition.
 20. The composition according to claim 18, wherein, the at least one photopolymerizable olefinic monomer accounts for 25% to 70% by weight of the composition, preferably, the at least one photopolymerizable olefinic monomer accounts for 25% to 65% by weight of the composition, preferably, the at least one photopolymerizable olefinic monomer accounts for 30% to 60% by weight of the composition, preferably, the at least one photopolymerizable olefinic monomer accounts for 35% to 55% by weight of the composition.
 21. The composition according to claim 18, wherein, the diamine accounts for 1% to 25% by weight of the composition, preferably, the diamine accounts for 1% to 15% by weight of the composition, preferably, the diamine accounts for 1% to 10% by weight of the composition, preferably, the diamine accounts for 1% to 5% by weight of the composition.
 22. The composition according to claim 18, wherein, the at least one photoinitiator accounts for 0.1% to 5% by weight of the composition, preferably, the at least one photoinitiator accounts for 1% to 3% by weight of the composition.
 23. The composition according to claim 18, wherein, the pigment accounts for 0% to 5% by weight of the composition.
 24. The composition according to claim 18, wherein the photopolymerizable olefinic monomer is an acrylate or a methacrylate; preferably, the photopolymerizable olefinic monomer has the structure of (XIV):

wherein, R⁵ is H or methyl, R⁶ is C₁ to C₃₆ hydrocarbyl, substituted C₁ to C₃₆ hydrocarbyl, heteroatom-containing C₁ to C₃₆ hydrocarbyl, or substituted and heteroatom-containing C₁ to C₃₆ hydrocarbyl, preferably, R⁶ comprises a C₆ to C₃₆ alicyclic moiety, more preferably, R⁶ is isobornene.
 25. The composition according to claim 18, wherein, the diamine has the structure of (XV): H₂N—L¹—NH₂   formula (XV) wherein, L¹ is an unsubstituted C₂ to C₁₄ alkylene group, substituted C₂ to C₁₄ alkylene group, heteroatom-containing C₂ to C₁₄ alkylene group, and substituted heteroatom-containing C₂ to C₁₄ alkylene group; preferably, L¹ is an unsubstituted C₂ to C₁₄ alkylene group. 26-55. (canceled)
 56. Application of prepolymer described in claim 1 in forming an article; preferably, the prepolymer is additively manufactured to form the article; preferably, the article is a three-dimensional article.
 57. Application of the curable resin composition described in claim 18 in forming an article; preferably, the curable resin composition is additively manufactured to form the article; preferably, the article is a three-dimensional article. 